Years ago, I wrote a short instrumental piece using OpenMPT, intended for use in an exercise routine, but didn't publish it. This is an arrangement of my piece in FamiTracker and in another engine.

This NSF was not generated from this FTM. The FTM is MMC5, while the NSF is 2A03-only, playing both 2A03 pulse 1 (chords) and MMC5 pulse 1 (ostinato) tracks through the 2A03 pulse 1 channel. Its engine allows a melodic track to interrupt pulse 1 the way triangle drums interrupt the bass line.

This'd be so much easier if FT supported interruption. I'm about to put in a request.

Any channel on a PSG can have this interruption as long as it has software-defined envelopes and instant timbre switching. (SID lacks software envelopes, as do pulses and noise on Game Boy. Samplers don't switch timbre seamlessly.) It's essentially an extension of the common "kick drum interrupts bass" pattern on triangle to melodic tracks.